I have not done it, but I think there is a screw on the top for your up-down adjustment and I would think also a screw on the side for your side to side adj.
get a buddy to park his car (regular sized sedan) about 25 feet in front of you, then adjust so your low beams are just below his mirrors.

X2 to what above posters said. One thing, if these are after market headlights, dont be surprised if getting aim perfect is difficult, if not impossible. I manage a body shop for a living, and had repaired my 04 a couple of times, so I have seen this happen quite a bit. The A/M's never did aim right